The Srebarna Nature Reserve (44°07'N, 27°04'E) is a World Heritage Site located on a freshwater lake of 900 hectares on the Romanian border, supplied by seasonal floods from the River Danube just one kilometer (k) to the north. It is the breeding home of 99 species of birds, 24 of which are rare or endangered. Some 80 other bird species migrate and overwinter there.
Threats to the site
The site was inscribed on the List of the World Heritage in Danger in 1992 as a result of progressive deterioration of the habitat of the bird populations. The prevention of seasonal flooding by the Iron Gates Dam upstream in Romania, and increased farmland pollution, degraded the water quality and the biological productivity of the lake which began to dry into a marsh, and led to the decline and disappearance of many birds, and affecting the site's Dalmatian pelican colony, 10% of the world's population.
In 1994 two new canals permitting a flow of water to the Reserve began to restore the condition of the lake. Adjacent lands were added to the Reserve, and all agricultural and residential activities affecting the lake were halted. By June 2002, total recovery of the Dalmatian pelican population and the gradual return to health of the Reserve were assured and Srebarna was removed from the List of World Heritage in Danger the following year.
Lake Srebarna lies in the flood plain of the Danube 1 km south of the river, on the northeastern Bulgarian border with Romania, 18 km west of the town of Silistra and 85 km southeast of Bucharest: 44°07'N, 27°04'E.
Date and history of establishment
- 1942: Declared a wildfowl refuge;
- 1948: Established as a Nature Reserve by the Ministry of Agriculture & Food by Decree 2-11-931;
- 1975: Designated a Wetland of International Importance under the Ramsar Convention;
- 1977: Recognized as a Biosphere Reserve under UNESCO's Man and the Biosphere Program;
- 1983: A buffer area was added around the Reserve;
- 1993: Nature Reserve area increased by 302 ha by Ordinance 581.
902 ha: Reserve (now including the islands of Devna, Vetrine and Komlouka in the Danube); 602 hectares (ha): Ramsar site; 542.8: buffer zone.
State, in Silistra province. Administered by the Ministry of Environment and Waters.
Approximately 10 -13.2 meters (m).
Srebarna is Bulgaria’s largest river lake. It lies in the floodplain of the River Danube on sandy clay and clay over limestone. It was connected to the river until the construction of flood-control dikes in 1948 and 1978 which first hindered then prevented its annual flooding. From then on it was fed largely by underground springs with some run-off from the surrounding hills. But after drought between 1982 and 1994, the water fell to an average depth of one meter and became hyper-eutrophic with nitrogen and phosphorus from farm wastes, fertilizers, pesticides and sediment. The lake began to turn into a marsh with effects on phytoplankton, fish and bird life. It was reconnected with river water, partially in 1979 and completely in 1994. By 1999 the mean depth had recovered to 2.1 m and the maximum was 3.3 m. There are now about 120 ha of open water with over 400 ha of reed beds. The surrounding land is marshy, but just beyond the boundaries are low hills and farms.
Northern Bulgaria has a continental climate of hot summers and cold wet winters. The mean January temperature is ~ -2ºC, the extreme minimum ~ -35ºC. The mean July temperature is 23ºC, the extreme maximum, 41ºC. The average annual rainfall is 502 millimeters (mm). Summers have become drier over the last 25 years.
Srebarna is floristically a region of the Ukraine-Kazakh biotic province and is the only protected tract of natural land of any size in the lower Danube wetlands of northeastern Bulgaria. It has 139 taxa, (53% of Bulgaria’s wetland species) in a variety of wetland habitats: standing and temporary open water with submerged vegetation, river, seasonal marsh, reed beds, swamp, hay meadows and poplar plantations. The dominant vegetation, covering two thirds of the reserve and forming a thick barrier around the lake, is the reed community Phragmites australis with lesser and greater reed-mace Typha angustifolia and T.latifolia and Schoenoplectus spp. It has mats of water lily Nymphaea alba and bushes of goat willow Salix caprea, grey willow S.cinerea and purple osier S.purpurea. It has 2 internationally and 11 nationally threatened species of plants.
The avifauna is very rich: 233 bird species including 80 migratory species, (55% of Bulgarian species), 24 of which give the Reserve its unique status as refuge for threatened or vulnerable species. It is important for breeding waterbirds. There are 99 breeding species, and the only Bulgarian colonies of Dalmatian pelican Pelecanus crispus (V) (80 pairs in 1999) and great egret Egretta alba (10-15 pairs). The reserve is the only nesting place in Bulgaria for black cormorants Phalacrocorax carbo (90-540 pairs) and ferruginous duck Aythya nyroca (V: 60 pairs), and is the largest wintering ground for red-breasted goose Branta ruficollis (V: 20-50 pairs). It is an important breeding ground for little cormorants Phalacrocorax pygmaeus (15 pairs), night heron Nycticorax nycticorax (50-150 pairs), squacco heron Ardeola rallioides (60 pairs), little bittern Ixobrychus minutus (20 pairs), glossy ibis Plegadis falcinellus (5 pairs), white spoonbill Platalea leucorodia (6-20 pairs), corncrake Crex crex (V), great bustard Otis tarda and five other heron species with some 1,000 nests. Important wintering species include mute swan Cygnus olor, white-fronted and greylag goose Anser albifrons and A. anser and white-tailed eagle Haliaeetus albicilla. It is a refuge for 12 internationally and 57 nationally threatened species.
There are 41 species of mammals nearly half of Bulgaria's fauna: 4 carnivores, 7 mustelids, 3 ungulates and 18 or more rodents. There are 6 nationally and 4 internationally threatened mammals: otters Lutra lutra (T) which are occasionally found, steppe polecat Mustella eversmanni, masked polecat Vormela peregusna and European wild cat Felis silvestris. Jackals Canis aureus, muskrats Ondatia zibethica, and racoon dogs Nyctereutes procyonoides have invaded the area, preying on the birds when they can, and wild boar Sus scrofa, roe deer Capreolus capreolus, red deer Cervus elaphus and hares Lepis sp. are still hunted nearby. There are 18 species of fish, 6 being endangered in Bulgaria including the rare asp Aspius aspius, 15 species of reptiles including the Aesculapian snake Elaphe longissimus, and 12 amphibians; one, the eastern spadefoot Pelobates syriacus, recently discovered in Bulgaria for the first time, is listed in the Red Book for Bulgaria.
Roman and later remains have been found just northeast of the Reserve at the fishing village of Vetren. Local people preserve traditional customs and dress, and there is an old settlement of the ultra-conservative Old Russian Believers in Tatarista in the next village east.
Local human population
Visitors and visitor facilities
There is a natural history museum in Srebarna which records 15,000 visitors, a third being students, and a hide for viewing the pelicans, but commercialism, tourism and hunting in the Reserve are strictly prohibited. The riverbanks are popular for fishing and picnicking and there are hotels at Vetren and Silistra.
Scientific research and facilities
The Reserve is a relatively fragile ecosystem and only carefully controlled scientific research is allowed. It has been studied for several years mainly to establish the numbers of different species and the ecological conditions necessary for their long-term preservation. There is a museum and a field station of the Central Laboratory for General Ecology in Srebarna village.
The Reserve is a prime area of lower Danube freshwater wetland, the breeding ground of 99 species of birds, some of which are globally threatened and several of which are vulnerable. The population of the Dalmatian pelican is 10% of the world total. Some 80 other bird species migrate and seek refuge here every winter.
Partial reconnection of the lake with the Danube in 1978, completed in 1994, was done to prevent the lake drying up and to restore its plant, fish and bird populations, but droughts, especially from 1985-1990, were destructive. In 1989 only 29 pairs of Dalmatian pelicans nested. However, artificial nesting platforms were built and fenced round and an average of 80 pairs now breed successfully. Other mitigation was also successful, the lake’s level restored and a management plan incorporating detailed research was funded following a WHC/IUCN/Ramsar mission in 1997. The whole reserve is well fenced and there is a buffer zone of 545 ha. Shooting is prohibited and access and the reserve is strictly limited to scientific staff with permits. In both 1998 and 2001 WHC/IUCN/Ramsar missions to the site were progressively impressed by the improvements achieved.
The establishment with Romania of a trans-boundary Danube Wetland World Heritage site has been suggested by the World Heritage Committee, including both banks and islands in the river. The management plan was published in 2000. It is very well researched and documented, detailing 24 categories of natural resource with recommendations for their treatment. It recorded the total recovery of the Dalmatian pelican population and the gradual recovery of the Reserve. Conditional on its acceptance by the World Heritage Committee and commitment of the funding needed for future action, Srebarna was removed from the danger list in June 2002.
The causes of the degradation of the lake and its wildlife were many but have now been largely overcome: cutting off water from the site by a flood-control dike in 1948, abandoning the reed harvest from 1975, dislocation of the seasonal flooding regime by the Iron Gates dam upstream in Romania, which also lowered the river bed, pumping of the lake’s underground supply, increased pollution of the diminishing lake, from farm wastes, fertilizers, pesticides and siltation from eroded slopes, shooting, fires, poison set for rodents, human disturbance and a long period of droughts between 1982 and 1994. Together these induced many harmful changes in the ecosystem: severe nutrient enrichment which degraded the hydrology and biological productivity of the lake; rapid acceleration in vegetational succession; the formation of algal blooms and toxic gases; dieback of higher submerged vegetation and bottom fauna, depriving the fish and birds of food, and increase in the size and density of the fringing reed beds, allowing wild boars, wild cats, foxes and jackals to prey on nests and on the 100-year old Dalmatian pelican colony. Many species of birds declined or disappeared. The lake began to dry into a marsh. International attention and a program of constant monitoring under the new plan should ensure that none of these occur again. In 2002 rapid sluicegate action to prevent future pollution was still needed.
In 2000 there was a resident manager and two guards. In addition, there were four scientists in the Ecological Field Station and five staff, including a biologist, in the Natural History Museum (undated information).
In 1997 SF 30,000 was granted towards a management plan from the Ramsar Small Grants Fund.
IUCN management category
- Ia Strict Nature Reserve. Ramsar Site.
- Biosphere Reserve
- Natural World Heritage Site, inscribed 1983. Natural Criterion iv.
- Listed as World Heritage in Danger 1992-2002 due to degradation following drought and water loss. De-listed in 2003.
- Bozhilova, E.D., Lazarova, M.A. and Strashevska, K. (1985). Geomorphological characteristics and development of the vegetation in the region of Srebarna Lake Bulgaria. Godishnik na Sofiiskiya Universitet "Kliment Okhridski" Biologicheski Fakultet 79(2): 99-109. (In Bulgarian).
- Bulgarian Academy of Sciences (2000).Ramsar Site Management Plans - Bulgaria, Srebarna. Management Plan of the Srebarna Biosphere Reserve. Central Laboratory for General Ecology, Sofia. 115pp + appendices.
- Hodek, R. (1982). Der wanderer heim. Mitt. Orn. Ver, Wien. 6 (3,4,5).
- IUCN (1987). Directory of Wetlands of International Importance. IUCN Conservation Monitoring Centre. IUCN, Gland, Switzerland and UK, Cambridge. Pp 46-47. ISBN: 2831700140
- Kostadinova, I.(1996) Bulgaria, in Heath, M. & Evans,M. (2000). Important Bird Areas in Europe. Vol.2. BirdLife International, Cambridge, U.K. ISBN: 0946888361
- Michev, T.& Stoyneva,M. (1994). Srebarna case: habitat changes as reflected by waterfowl. In: Farago, S.,& Kerekes, J. (eds), Limnology and Waterfowl. Monitoring, Modelling and Management. SIL Working group on aquatic birds. Abstracts, Sarrod-Sopron, Nov.1994, p.32. ISBN: 9630474204
- Michev, T., Georgiev,B., Petrova,A. & Stoyneva, M. (eds), (1998). Biodiversitiy of the Srebarna Biosphere Reserve, checklist and bibliography. Sofia, Co-publishers, Context & Pensoft, xiv + 130 pp.
- Mikhov, N., Marinov, M., Michev, T.,Iankov, P.& Kurtev, M. (1997). Srebarna Lake. In: Kostadinova, I. (comp.), 1997. Ornithological Important Areas in Bulgaria. Sofia: pp.106-108 (Engl. summ.).
- Mikhov, N. & Kutzarov, Y. (n.d.) A Checklist of the Birds of Srebarna Biosphere Reserve (manuscript). Bulgarian Academy of Sciences, Central Laboratory for General Ecology, Sofia. 6 pp.
- Ministry of Environment (n.d.). National Action Plan for the Conservation of the Most Important Wetlands in Bulgaria. Sofia.
- Mountfort, G.,& Ferguson-Lees, I. 1961. Observations on the birds of Bulgaria. Ibis 103a:443-471.
- Stoilov, D., Noshtev, V., Gerasimov, S. & Velev, V. (1981). Protected Natural Sites in the People's Republic of Bulgaria. Balkan State Printing House: Sofia.
- Stoyneva, M. & Michev,T. (1998). Srebarna: general characteristics and brief history. In: Michev, T., Georgiev, B., Petrova, A. & Stoyneva, M. (1998). Biodiversity of the Srebarna Biosphere Reserve. Checklist and Bibliography. Sofia, Co-publishers Context & Pensoft, pp.1-8. ISBN: 9546420484
- UNESCO World Heritage Committee (1999). Report on the 22nd Session of the World Heritage Bureau Paris.
- UNESCO World Heritage Committee (2002). Report on the 26th Session of the World Heritage Bureau, Paris.
- Van Lent, T. & Soukup, M. (1993). Restoration of Srebarna, World Heritage Site. Report to Ramsar Convention Bureau. National Park Service, Washington, U.S.A.
- Vodenicharov, D. & Nicoloff, H. (1991). Report to Ramsar Convention Bureau. Ministry of Environment, Sofia.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the United Nations Environment Programme-World Conservation Monitoring Centre (UNEP-WCMC). Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the United Nations Environment Programme-World Conservation Monitoring Centre (UNEP-WCMC) should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.